The greening of the earth is reaching its limit

19 de September 2017

A new study led by Josep Peñuelas and published in Nature Ecology and Evolution reveals that CO2 abundance in the atmosphere no longer has a powerful fertilizing effect on vegetation. The greening that has been observed in recent years is slowing and this will cause CO2 levels in the atmosphere to rise, thus increasing temperatures and leading to increasingly severe changes in climate.

Foto: Josep Fuster (CC-BY)

Foto: Josep Fuster (CC-BY)

Terrestrial ecosystems are showing signs of saturation and their capacity for atmospheric carbon capture is weakening. Global warming is also making these ecosystems less productive, especially during heat waves. A study published in the journal Nature Ecology & Evolution led by the CSIC researcher at CREAF Josep Peñuelas concludes that lower ecosystem productivity and a deceleration in carbon capture will lead to a change in scenery..

From a global scenario dominated by the positive effects of carbon and nitrogen fertilization, we will move to another characterized by ecosystem saturation and greater climate change impacts," says Dr. Peñuelas.

Terrestrial ecosystems annually remove about one-third of the carbon dioxide emissions generated by fossil fuel use, industry, and land-use change. “If human emissions continue to increase and ecosystems are becoming less efficient in removing carbon, we will move from a scenario where excess CO2 is no longer acting as a fertilizer favoring vegetation growth into a period where the greater amount of atmospheric carbon accelerates global warming, “explains Peñuelas. In fact, “not only will ecosystems be able to sequester less and less carbon, but carbon will remain less time in plants and soils and will be returned to the atmosphere sooner“, adds Jordi Sardans, study coauthor and researcher at CREAF.

Nutrient scarcity means that vegetation growth is limited

Through carbon capture, ecosystems act as a buffer slowing the effects of increased CO2 and reduce the impacts of climate change. But the current lack of other nutrients such as potassium, and more crucially, phosphorus, as well as changes in the climate, are becoming major obstacles to plant growth.  “In the future, it will be nutrient availability which sets the capacity of vegetation to take carbon out of the atmosphere.

We need a better understanding of the phosphorus cycle functions and what factors regulate its circulation in ecosystems," says Marcos Fernández Martínez, study coauthor and researcher at CREAF.

“The severity of climatic phenomena such as droughts are also especially negative for plant productivity, above all if they occur in periods of vegetation growth,” says  Jofre Carnicer, study author and CREAF researcher.  In fact, a global temperature increase of 2° C would not cause much of an increase in the frequency of heat waves, but an increase of 3° C would result in summers as warm as in 2003 every three or four years, affecting carbon capture in forests much more that has occurred to date.

During 2015 there were large fires in Southeast Asia, coral bleaching in Australia, droughts in Africa, and floods in South America associated with El Niño; all of this was fueled by record temperatures and serve as examples of this transition to a warmer world. Therefore, “we need a better understanding of the impacts of climate change and what mitigation measures should be applied to meet the COP21 agreements on rising global temperatures,” concludes the lead author of the study, Josep Peñuelas.

 REFERENCED ARTICLE

Peñuelas J., Ciais P., Canadell JG., Janssens I., Fernandez-Martinez M., Carnicer J., Obersteiner M., Piao S., Vautard R., Sardans J. (2017). Shifting from a fertilization-dominated to a warming-dominated period. Nature Ecology & Evolution, DOI: 10.1038/s41559-017-0274-8

, , , , , , , , , , , , , , ,

Albert Naya i Díaz
Fascinated by the singularity of our Earth, I have recently travelled out of necessity. Shortly before that I followed a trainee program to become a Science teacher, which has always been my dream. Even before that, I had completed a degree in Environmental Science (2010-14) and previously, I had studied Journalism for four years (2006-10), always at the UAB. All these have helped me to join CREAF as a Communication Technician on the 2nd of Dec 2015.
Related articles
, , ,
Four Spanish scientists receive the Nature award
5 de December 2017CREAF
For the time being, forests are helping to slow CO2 accumulation and climate change
4 de December 2017Albert Naya i Díaz
Fossil fuel emissions hit record high after unexpected growth: Global Carbon Budget 2017
16 de November 2017CREAF
Russian Revolution and environment
25 de October 2017Jaume Terradas
Citizen science is a useful and reliable tool for studying the mosquitoes driving global epidemics
24 de October 2017Marina Torres Gibert

Follow CREAF on: